Server overhaul: clear clippy::pedantic wins

Taken from a -W clippy::pedantic scan, no allow added: map_or/map_or_else, method references instead of closures,
clone_from, write! instead of push_str(format!), borrowed Option<&str>, push_of without a needless Option, the
envelope's entity moved instead of cloned, the scheduler's plan() no longer a needless async fn (its doc now says
what it does on failure), sort_unstable, digit separators and inline format args in tests. Not taken: missing
# Errors/# Panics docs, must_use, doc backticks, assert!(x.is_empty()) in tests, too_many_lines.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

server/crates/kvitt-server/src/sync/push.rs

@@ -57,7 +57,7 @@ fn canonical_uuid(value: Option<&Value>) -> Option<Uuid> {
         .filter(|id| id.hyphenated().to_string() == text)
 }
 
-fn envelope(index: usize, raw: Value) -> Result<Envelope, AppError> {
+fn envelope(index: usize, mut raw: Value) -> Result<Envelope, AppError> {
     let bad = |what: &str| {
         AppError::invalid_request(format!("mutations[{index}]: {what}")).with_field("mutations")
     };
@@ -68,7 +68,10 @@ fn envelope(index: usize, raw: Value) -> Result<Envelope, AppError> {
         Some("settlement") => EntityType::Settlement,
         _ => return Err(bad("entity_type must be expense or settlement")),
     };
-    let entity = raw.get("entity").cloned().unwrap_or(Value::Null);
+    let entity = raw
+        .get_mut("entity")
+        .map(Value::take)
+        .unwrap_or(Value::Null);
     let entity_id = canonical_uuid(entity.get("id"))
         .ok_or_else(|| bad("entity.id must be a lowercase hyphenated uuid"))?;
     Ok(Envelope {
@@ -410,13 +413,13 @@ fn rejected(env: &Envelope, rejection: Rejection, current: Option<SyncEntity>) -
     })
 }
 
-fn push_of(push_type: PushType, env: &Envelope, ctx: &Ctx<'_>) -> Option<PushMessage> {
-    Some(PushMessage {
+fn push_of(push_type: PushType, env: &Envelope, ctx: &Ctx<'_>) -> PushMessage {
+    PushMessage {
         push_type,
         entity_id: Some(env.entity_id),
         actor_user_id: ctx.caller.user_id,
         count: 1,
-    })
+    }
 }
 
 async fn reload<K: Kind>(conn: &mut SqliteConnection, id: Uuid) -> Result<K::Wire, AppError> {
@@ -552,7 +555,7 @@ async fn process<K: Kind>(
             .await?;
             return Ok(Processed {
                 result: accepted(env, K::entity(after)),
-                push: push_of(K::DELETED, env, ctx),
+                push: Some(push_of(K::DELETED, env, ctx)),
             });
         }
         // Created and deleted before it ever synced: store the tombstone, no audit, no push. It is validated like a
@@ -595,7 +598,7 @@ async fn process<K: Kind>(
         .await?;
         return Ok(Processed {
             result: accepted(env, K::entity(after)),
-            push: push_of(K::CREATED, env, ctx),
+            push: Some(push_of(K::CREATED, env, ctx)),
         });
     };
 
@@ -638,7 +641,7 @@ async fn process<K: Kind>(
     .await?;
     Ok(Processed {
         result: accepted(env, K::entity(after)),
-        push: push_of(K::UPDATED, env, ctx),
+        push: Some(push_of(K::UPDATED, env, ctx)),
     })
 }